Animal Structure and Function
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36 – Animal Structure and Function
working together in unison are considered a tissue.
tissues working together are called an organ.
Different types of tissue have different structures to improve their
organs working together are called an organ system
organ systems working together make an organism.
are divided into four main categories
Covers the outside of the body
Lines organs and internal cavities
Acts as a barrier to injury, organisms, or fluid loss.
Free surface is exposed to fluid or air.
Cells are attached to a basement membrane which is a dense mat of
extracellular matrix that holds the cells in place.
Divided into several smaller categories
epithelium – made of one layer. Only
one layer of cells is touching the basement membrane
epithelium – made of many layers of cells and only one layer is in contact
with the basement membrane.
epithelium – Appears to have multiple layers because the cells are elongated
but all cells involved touch the basement membrane.
– cube shaped
Also absorb or secrete chemical solutions like the mucous membrane.
Binds and supports other tissues.
Sparse population of cells scattered throughout the matrix.
consists of a web of fibers embedded in a uniform foundation that may be liquid,
jellylike or solid.
Made of three kinds of proteins
fibers – made of collagen that are nonelastic and do not tear easily when
fibers – long threads of elastin and provide a rubbery quality that lets the
tissue return to its normal shape.
fibers – very thin and branched, composed of collagen and join connective
tissue to adjacent tissues.
Six major types
connective tissue – binds epithelia to underlying tissues and functions as a
packing material. Contains all
three types of fibers.
are fibroblasts, which secrete the protein ingredients of the extracellular
fibers, and macrophages that engulf bacteria and debris of dead cells by
tissue – Stores fat throughout the matrix, which pads and insulates the body.
Contains a large fat droplet that swells when fat is stored and shrinks
when it is used.
connective tissue – Dense due to collagenous fibers. Arranged in parallel bundles that maximizes nonelastic
are tendons that join muscle to bone and ligaments that join bone to bone.
– Made of collagenous fibers embedded in a substance called chondroitin
sulfate that is secreted by Chondrocytes. These
cells are found in the lacunae making it strong yet flexible.
Mineralized connective tissue formed by Osteoblasts that deposit a matrix of
collagen as well as calcium, magnesium, and phosphate ions, which harden within
the matrix. Forms in repeating
units called halversian canals that contain concentric layers of the matrix
surrounding a central canal containing blood vessels and nerves.
Osteocytes are found in the lacunae and destroy old bone matter and
replace it with new matter to improve the strength.
The interior is spongy bone tissue filled with bone marrow that
manufactures red blood cells.
does not have an extracellular matrix but is made of liquid called plasma
containing water, salts, and dissolved proteins. The plasma contains erythrocytes or red blood cells and
leukocytes or white blood cells. It
also contains platelets that help with clotting.
Senses stimuli and transmits signals from one part of the animal to
another. The functioning unit is
called the neuron, which is made of a cell body containing the organelles and
dendrites, and axons, which transmit the signals.
transmit impulses from their tip toward the rest of the neuron.
transmit impulses toward another neuron or toward an effector.
Composed of long cells called muscle fibers that are capable of
contracting when stimulated by nerve impulses.
in parallel and made of microfilaments called actin and myosin.
types of muscle exist.
muscle, which is responsible for voluntary movements of the body.
It is also striated because of the overlapping filaments.
muscle forms the heart. It is also
striated but branched and then ends are joined by intercalated discs, which
relay signals from cell to cell.
muscle lacks the striations and is found in the walls of internal organs.
Cells are spindle shaped and contract more slowly but remain contracted
systems are interdependent
made of 11 different organ systems
chemical energy from food by using enzymes to digest it and then body cells
absorb it. These cells must use
cellular respiration to convert the energy to ATP. Animals are constantly undergoing this process.
amount of energy an animal uses is called its metabolic rate and the energy is
measured in calories.
Minimal metabolic rates support the basic functions needed to maintain
Extremes can cause changes in this metabolic rate.
The basal metabolic rate is the number of calories an animal uses at rest
with an empty stomach and experiencing no stress.
Ectotherms have a standard metabolic rate.
the internal environment
Bernard made a distinction between the internal and external environment of an
internal environment is called the interstitial fluid.
This fluid fills the spaces between our cells, exchanges nutrients and
wastes with blood contained in capillaries.
Animals attempt to maintain relatively constant conditions even when the
external environment changes.
concentration in blood
Referred to as homeostasis
on feedback circuits made of a receptor, a control center and an effector.
receptor detects a change in some variable in the internal environment.
control center process information it receives and directs and appropriate
effector takes the information about the response from the control center and
puts the change into action.
negative feedback takes place when a change in the variable triggers the control
mechanism to counteract further changes in the same direction.
These prevent small changes from becoming too large.
feedback involves a change in some variable that triggers mechanisms that
amplify rather than reverse change. An
example is childbirth.
changes are required for normal body functions.
5. Often these are cyclic like with changes in hormone levels.